MAPREDUCE-5240. Fix a bug in MRAppMaster because of which OutputCommitter could not access credentials set by the user. Contributed by Vinod Kumar Vavilapalli.
svn merge --ignore-ancestry -c 1482175 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482176 13f79535-47bb-0310-9956-ffa450edef68